The present invention relates to rechargeable battery packs generally and more particularly to battery packs for use with cellular telephones and other portable devices.
Modern, small size, high-performance cellular telephones are currently powered by nickel-metal or lithium-ion cells which are characterized by efficient power storage and output both at low and high output power.
Alkaline batteries are well known for many applications but are not preferred for powering cellular telephones, because of their relatively low efficiency at peak power outputs used during telephone transmission.
The present invention seeks to provide an improved rechargeable battery pack particularly suitable for use with cellular telephones as well as a cellular telephone including an improved battery pack.
There is thus provided in accordance with a preferred embodiment of the present invention an improved rechargeable battery pack particularly suitable for use with cellular telephones or other portable devices as well as a cellular telephone including an improved battery pack wherein the battery pack includes:
at least one rechargeable cell providing relatively efficient stored energy output at both relatively high and relatively low output current levels;
at least one primary cell providing efficient stored energy output at relatively low output current levels and relatively inefficient stored energy output at relatively high output current levels; and
a rechargeable cell recharger, receiving an output from the at least one primary cell at said relatively low output current level.
Preferably, a user operable switch is provided to selectably supply power from the at least one primary cell to the rechargeable cell recharger.
There is also provided in accordance with a preferred embodiment of the present invention an improved rechargeable battery pack particularly suitable for use with cellular telephones as well as a cellular telephone including an improved battery pack wherein the battery pack includes:
at least one rechargeable cell providing relatively efficient stored energy output at both relatively high and relatively low output current levels;
a receptacle for receiving at least one primary cell providing efficient stored energy output at relatively low output current levels and relatively inefficient stored energy output at relatively high output current levels; and
a rechargeable cell recharger, responsive to an output from the at least one primary cell at said relatively low output current level for recharging the at least one rechargeable cell.
It is a particular feature of the present invention that a primary cell can thus be efficiently used to power an application having high current level power requirements but using the primary cell to charge a rechargeable cell at a relatively low current level. This feature is even more significant in view of the fact that most primary cells store energy more efficiently that most rechargeable cells.
In accordance with a preferred embodiment of the present invention the rechargeable cell recharger also comprises line voltage recharging circuitry which receives power at a line voltage and which is operative to recharge a rechargeable cell with or without recharging the primary cell.
Additionally in accordance with a preferred embodiment of the present invention the battery pack also includes circuitry for limiting the amount of recharging of the rechargeable cell from the at least one primary cell according to the amount that the rechargeable cell is charged.
The rechargeable cell is preferably a lithium-ion or nickel-metal cell, while the primary cell is preferably an alkaline battery such as a conventional AA or AAA cell.